1
|
Abstract
The field of cAMP signaling is witnessing exciting developments with the recognition that cAMP is compartmentalized and that spatial regulation of cAMP is critical for faithful signal coding. This realization has changed our understanding of cAMP signaling from a model in which cAMP connects a receptor at the plasma membrane to an intracellular effector in a linear pathway to a model in which cAMP signals propagate within a complex network of alternative branches and the specific functional outcome strictly depends on local regulation of cAMP levels and on selective activation of a limited number of branches within the network. In this review, we cover some of the early studies and summarize more recent evidence supporting the model of compartmentalized cAMP signaling, and we discuss how this knowledge is starting to provide original mechanistic insight into cell physiology and a novel framework for the identification of disease mechanisms that potentially opens new avenues for therapeutic interventions.
Collapse
Affiliation(s)
- Manuela Zaccolo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Anna Zerio
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Miguel J Lobo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| |
Collapse
|
2
|
van der Horst J, Greenwood IA, Jepps TA. Cyclic AMP-Dependent Regulation of Kv7 Voltage-Gated Potassium Channels. Front Physiol 2020; 11:727. [PMID: 32695022 PMCID: PMC7338754 DOI: 10.3389/fphys.2020.00727] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 06/04/2020] [Indexed: 01/08/2023] Open
Abstract
Voltage-gated Kv7 potassium channels, encoded by KCNQ genes, have major physiological impacts cardiac myocytes, neurons, epithelial cells, and smooth muscle cells. Cyclic adenosine monophosphate (cAMP), a well-known intracellular secondary messenger, can activate numerous downstream effector proteins, generating downstream signaling pathways that regulate many functions in cells. A role for cAMP in ion channel regulation has been established, and recent findings show that cAMP signaling plays a role in Kv7 channel regulation. Although cAMP signaling is recognized to regulate Kv7 channels, the precise molecular mechanism behind the cAMP-dependent regulation of Kv7 channels is complex. This review will summarize recent research findings that support the mechanisms of cAMP-dependent regulation of Kv7 channels.
Collapse
Affiliation(s)
- Jennifer van der Horst
- Vascular Biology Group, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Iain A Greenwood
- Molecular and Clinical Sciences Institute, St. George's University of London, London, United Kingdom
| | - Thomas A Jepps
- Vascular Biology Group, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| |
Collapse
|
3
|
Wang X, Fitts RH. Cardiomyocyte slowly activating delayed rectifier potassium channel: regulation by exercise and β-adrenergic signaling. J Appl Physiol (1985) 2020; 128:1177-1185. [DOI: 10.1152/japplphysiol.00802.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Results demonstrate that exercise training (TRN) downregulates ventricular IKs channel current and the channel’s responsiveness to β-agonist factors mediated by TRN-induced decline in channel subunits KCNQ1 and KCNE1 and the A-kinase anchoring protein yotiao. The reduced IKs current helps explain the TRN-induced prolongation of the action potential in basal conditions and, coupled with previously reported upregulation of the KATP channel, results in a more efficient heart that is better able to respond to beat-by-beat changes in metabolism.
Collapse
Affiliation(s)
- Xinrui Wang
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
| | - Robert H. Fitts
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
| |
Collapse
|
4
|
Wu YS, Chen CC, Chien CL, Lai HL, Jiang ST, Chen YC, Lai LP, Hsiao WF, Chen WP, Chern Y. The type VI adenylyl cyclase protects cardiomyocytes from β-adrenergic stress by a PKA/STAT3-dependent pathway. J Biomed Sci 2017; 24:68. [PMID: 28870220 PMCID: PMC5584049 DOI: 10.1186/s12929-017-0367-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 08/11/2017] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND The type VI adenylyl cyclase (AC6) is a main contributor of cAMP production in the heart. The amino acid (aa) sequence of AC6 is highly homologous to that of another major cardiac adenylyl cyclase, AC5, except for its N-terminus (AC6-N, aa 1-86). Activation of AC6, rather than AC5, produces cardioprotective effects against heart failure, while the underlying mechanism remains to be unveiled. Using an AC6-null (AC6-/-) mouse and a knockin mouse with AC6-N deletion (AC6 ΔN/ΔN), we aimed to investigate the cardioprotective mechanism of AC6 in the heart. METHODS Western blot analysis and immunofluorescence staining were performed to determine the intracellular distribution of AC6, AC6-ΔN (a truncated AC6 lacking the first 86 amino acids), and STAT3 activation. Activities of AC6 and AC6-ΔN in the heart were assessed by cAMP assay. Apoptosis of cardiomyocytes were evaluated by the TUNEL assay and a propidium iodine-based survival assay. Fibrosis was examined by collagen staining. RESULTS Immunofluorescence staining revealed that cardiac AC6 was mainly anchored on the sarcolemmal membranes, while AC6-ΔN was redistributed to the sarcoplasmic reticulum. AC6ΔN/ΔN and AC6-/- mice had more apoptotic myocytes and cardiac remodeling than WT mice in experimental models of isoproterenol (ISO)-induced myocardial injury. Adult cardiomyocytes isolated from AC6ΔN/ΔN or AC6-/- mice survived poorly after exposure to ISO, which produced no effect on WT cardiomyocytes under the condition tested. Importantly, ISO treatment induced cardiac STAT3 phosphorylation/activation in WT mice, but not in AC6ΔN/ΔN and AC6-/- mice. Pharmacological blockage of PKA-, Src-, or STAT3- pathway markedly reduced the survival of WT myocytes in the presence of ISO, but did not affect those of AC6ΔN/ΔN and AC6-/- myocytes, suggesting an important role of AC6 in mediating cardioprotective action through the activation of PKA-Src-STAT3-signaling. CONCLUSIONS Collectively, AC6-N controls the anchorage of cardiac AC6 on the sarcolemmal membrane, which enables the coupling of AC6 with the pro-survival PKA-STAT3 pathway. Our findings may facilitate the development of novel therapies for heart failure.
Collapse
Affiliation(s)
- Yu-Shuo Wu
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.,Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan
| | - Chien-Chang Chen
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.,Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan
| | - Chen-Li Chien
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.,Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan
| | - Hsing-Lin Lai
- Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan
| | - Si-Tse Jiang
- National Laboratory Animal Center, National Applied Research Laboratories, Tainan, Taiwan
| | - Yong-Cyuan Chen
- Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan
| | - Lin-Ping Lai
- Institute of Internal Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Wei-Fan Hsiao
- Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Wen-Pin Chen
- Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan.
| | - Yijuang Chern
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan. .,Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan.
| |
Collapse
|
5
|
Role of plasma membrane-associated AKAPs for the regulation of cardiac IK1 current by protein kinase A. Naunyn Schmiedebergs Arch Pharmacol 2017; 390:493-503. [DOI: 10.1007/s00210-017-1344-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 01/12/2017] [Indexed: 12/20/2022]
|
6
|
Choudhary I, Lee H, Pyo MJ, Heo Y, Bae SK, Kwon YC, Yoon WD, Kang C, Kim E. Proteomics approach to examine the cardiotoxic effects of Nemopilema nomurai Jellyfish venom. J Proteomics 2015; 128:123-31. [PMID: 26193491 DOI: 10.1016/j.jprot.2015.07.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Revised: 07/07/2015] [Accepted: 07/13/2015] [Indexed: 01/19/2023]
Abstract
UNLABELLED Nemopilema nomurai is one of the largest species of jellyfish in the world. It blooms mainly offshore of Korea, China, and Japan. Increasing population numbers of N. nomurai is increasing the risk of sea bathers to the jellyfish stings and accompanying envenomations. Cardiovascular effects, and cytotoxicity and hemolytic activities have been previously reported in rodent models. To understand the mechanism of cardiac toxicity, we examined the effect of N. nomurai jellyfish venom (NnV) at the proteome level on rat cardiomyocytes cell line H9c2 using two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS). Cells treated with NnV displayed dose-dependent inhibition of viability. Cellular changes at proteome level were investigated after 6h and 12h of venom treatment. Electrophoretic examination revealed 72 protein spots displaying significant quantitative changes. These proteins were analyzed by MALDI-TOF/MS. Thirty four differentially expressed proteins were successfully identified; 24 proteins increased in quantity and 10 proteins decreased, compared to the respective controls. Proteins altered in content in Western blot analyses included myosin VII, annexin A2, aldose reductase, suppressor of cytokine signaling 1 (SOCS1), and calumenin, which are well-known marker proteins of cardiac dysfunctions. BIOLOGICAL SIGNIFICANCE This is the first report revealing the cardiac toxicity of NnV at the proteome level. NnV directly targeted proteins involved in cardiac dysfunction or maintenance. Suppressor of cytokine signaling 1 (SOCS1), which inhibits the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway, was upregulated by NnV. Other proteins related to cardiac arrest that were over-expressed included aldose reductase and calumenin. These results clarify the underlying mechanism of cardiomyocyte damage caused by NnV. By inhibiting these particular targets and more precisely identifying the components of NnV-mediated cardiac toxicity, jellyfish venom-associated poisoning could be reduced or prevented.
Collapse
Affiliation(s)
- Indu Choudhary
- College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea
| | - Hyunkyoung Lee
- College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea
| | - Min-Jung Pyo
- College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea
| | - Yunwi Heo
- College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea
| | - Seong Kyeong Bae
- College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea
| | - Young Chul Kwon
- College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea
| | - Won Duk Yoon
- Headquarters for Marine Environment, National Fisheries Research & Development Institute, Shiran-ri, Gijang-eup, Gijang-gun, Busan 619-705, Republic of Korea
| | - Changkeun Kang
- College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea; Institutes of Agriculture and Life Science, Gyeongsang National University, Jinju, Republic of Korea
| | - Euikyung Kim
- College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea; Institute of Animal Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea.
| |
Collapse
|
7
|
Abstract
Ion channels are essential for basic cellular function and for processes including sensory perception and intercellular communication in multicellular organisms. Voltage-gated potassium (Kv) channels facilitate dynamic cellular repolarization during an action potential, opening in response to membrane depolarization to facilitate K+ efflux. In both excitable and nonexcitable cells other, constitutively active, K+ channels provide a relatively constant repolarizing force to control membrane potential, ion homeostasis, and secretory processes. Of the forty known human Kv channel pore-forming α subunits that coassemble in various combinations to form the fundamental tetrameric channel pore and voltage sensor module, KCNQ1 is unique. KCNQ1 stands alone in having the capacity to form either channels that are voltage-dependent and require membrane depolarization for activation, or constitutively active channels. In mammals, KCNQ1 regulates processes including gastric acid secretion, thyroid hormone biosynthesis, salt and glucose homeostasis, and cell volume and in some species is required for rhythmic beating of the heart. In this review, the author discusses the unique functional properties, regulation, cell biology, diverse physiological roles, and involvement in human disease states of this chameleonic K+ channel.
Collapse
|
8
|
Local termination of 3'-5'-cyclic adenosine monophosphate signals: the role of A kinase anchoring protein-tethered phosphodiesterases. J Cardiovasc Pharmacol 2012; 58:345-53. [PMID: 21654331 DOI: 10.1097/fjc.0b013e3182214f2b] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A kinase anchoring proteins (AKAPs) belong to a family of functionally related proteins capable of binding protein kinase A (PKA) and tether it to relevant targets. In this way, AKAPs organize macromolecular complexes to segregate PKA activity and retain signal specificity. In the heart, AKAP-PKA interaction is central to the regulation of cardiac contractility. Phosphodiesterases belong to a large superfamily of enzymes that degrade 3'-5'-cyclic adenosine monophosphate (cAMP). They possess diverse catalytic properties and multiple regulatory mechanisms and control the duration and amplitude of the cAMP signal, including its propagation in space. AKAPs, together with PKA, can also assemble phosphodiesterases thereby providing a means to locally control cAMP dynamics at the level of single macromolecular complexes. This allows for the fine tuning of the cAMP response to the specific demands of the cell.
Collapse
|
9
|
Abstract
A-kinase anchoring proteins (AKAPs) create compartmentalized environment inside the cell to bring various signaling molecules to their targets. In the heart, a slowly activating potassium channel (IKs) important for cardiac repolarization is tightly regulated by the sympathetic nervous system in an AKAP-dependent manner. IKs channel forms a macromolecular complex with AKAP9 and other enzymes, such as protein kinase A, phosphatase, adenylyl cyclase, and phosphodiesterase, all of which are responsible to control the phosphorylation state of the channel. Such a complex thus ensures the IKs channel to be regulated properly to maintain the normal cardiac rhythm. Disruptions of various elements of the complex have been found to cause severe pathological consequences, including the long QT syndrome.
Collapse
|
10
|
Mechanisms of protein kinase A anchoring. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 283:235-330. [PMID: 20801421 DOI: 10.1016/s1937-6448(10)83005-9] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The second messenger cyclic adenosine monophosphate (cAMP), which is produced by adenylyl cyclases following stimulation of G-protein-coupled receptors, exerts its effect mainly through the cAMP-dependent serine/threonine protein kinase A (PKA). Due to the ubiquitous nature of the cAMP/PKA system, PKA signaling pathways underlie strict spatial and temporal control to achieve specificity. A-kinase anchoring proteins (AKAPs) bind to the regulatory subunit dimer of the tetrameric PKA holoenzyme and thereby target PKA to defined cellular compartments in the vicinity of its substrates. AKAPs promote the termination of cAMP signals by recruiting phosphodiesterases and protein phosphatases, and the integration of signaling pathways by binding additional signaling proteins. AKAPs are a heterogeneous family of proteins that only display similarity within their PKA-binding domains, amphipathic helixes docking into a hydrophobic groove formed by the PKA regulatory subunit dimer. This review summarizes the current state of information on compartmentalized cAMP/PKA signaling with a major focus on structural aspects, evolution, diversity, and (patho)physiological functions of AKAPs and intends to outline newly emerging directions of the field, such as the elucidation of AKAP mutations and alterations of AKAP expression in human diseases, and the validation of AKAP-dependent protein-protein interactions as new drug targets. In addition, alternative PKA anchoring mechanisms employed by noncanonical AKAPs and PKA catalytic subunit-interacting proteins are illustrated.
Collapse
|
11
|
Dessauer CW. Adenylyl cyclase--A-kinase anchoring protein complexes: the next dimension in cAMP signaling. Mol Pharmacol 2009; 76:935-41. [PMID: 19684092 DOI: 10.1124/mol.109.059345] [Citation(s) in RCA: 192] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The formation of multiprotein complexes is a repeated theme in biology ranging from the regulation of the extracellular signal-regulated kinase and cAMP signaling pathways to the formation of postsynaptic density complexes or tight junctions. A-kinase anchoring proteins (AKAPs) are well known for their ability to scaffold protein kinase A and components upstream and downstream of cAMP production, including G protein-coupled receptors, cAMP-dependent Rap-exchange factors, and phosphodiesterases. Specific adenylyl cyclase (AC) isoforms have also been identified as components of AKAP complexes, namely AKAP79, Yotiao, and mAKAP. In this review, we summarize recent evidence for AC-AKAP complexes and requirements for compartmentalization of cAMP signaling. The ability of AKAPs to assemble intricate feedback loops to control spatiotemporal aspects of cAMP signaling adds yet another dimension to the classic cAMP pathway.
Collapse
Affiliation(s)
- Carmen W Dessauer
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
| |
Collapse
|
12
|
The A-kinase anchoring protein Yotiao binds and regulates adenylyl cyclase in brain. Proc Natl Acad Sci U S A 2008; 105:13835-40. [PMID: 18772391 DOI: 10.1073/pnas.0712100105] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A-kinase anchoring proteins (AKAPs) influence the spatial and temporal regulation of cAMP signaling events. Anchoring of PKA in proximity to certain adenylyl cyclase (AC) isoforms is thought to enhance the phosphorylation dependent termination of cAMP synthesis. Using a combination of immunoprecipitation and enzymological approaches, we show that the plasma membrane targeted anchoring protein AKAP9/Yotiao displays unique specificity for interaction and the regulation of a variety of AC isoforms. Yotiao inhibits AC 2 and 3, but has no effect on AC 1 or 9, serving purely as a scaffold for these latter isoforms. Thus, Yotiao represents an inhibitor of AC2. The N terminus of AC2 (AC2-NT), which binds directly to amino acids 808-957 of Yotiao, mediates this interaction. Additionally, AC2-NT and Yotiao (808-957) are able to effectively inhibit the association of AC2 with Yotiao and, thus, reverse the inhibition of AC2 by Yotiao in membranes. Finally, disruption of Yotiao-AC interactions gives rise to a 40% increase in brain AC activity, indicating that this anchoring protein functions to directly regulate cAMP production in the brain.
Collapse
|
13
|
Abstract
Background—
Inhibition of individual K
+
currents causes functionally based compensatory increases in other K
+
currents that minimize changes in action potential duration, a phenomenon known as repolarization reserve. The possibility that sustained K
+
channel inhibition may induce remodeling of ion current expression has not been tested. Accordingly, we assessed the effects of sustained inhibition of one K
+
current on various other cardiac ionic currents.
Methods and Results—
Adult canine left ventricular cardiomyocytes were incubated in primary culture and paced at a physiological rate (1 Hz) for 24 hours in the presence or absence of the highly selective rapid delayed-rectifier K
+
current (I
Kr
) blocker dofetilide (5 nmol/L). Sustained dofetilide exposure led to shortened action potential duration and increased repolarization reserve (manifested as a reduced action potential duration–prolonging response to I
Kr
blockade). These repolarization changes were accompanied by increased slow delayed-rectifier (I
Ks
) density, whereas I
Kr
, transient-outward (I
to
), inward-rectifier (I
K1
), L-type Ca
2+
(I
CaL
), and late Na
+
current remained unchanged. The mRNA expression corresponding to KvLQT1 and minK (real-time polymerase chain reaction) was unchanged, but their protein expression (Western blot) was increased, suggesting posttranscriptional regulation. To analyze possible mechanisms, we quantified the muscle-specific microRNA subtypes
miR
-133a and
miR
-133b, which can posttranscriptionally regulate and repress KvLQT1 protein expression without affecting mRNA expression. The expression levels of
miR
-133a and
miR
-133b were significantly decreased in cells cultured in dofetilide compared with control, possibly accounting for KvLQT1 protein upregulation.
Conclusions—
Sustained reductions in I
Kr
may lead to compensatory upregulation of I
Ks
through posttranscriptional upregulation of underlying subunits, likely mediated (at least partly) by microRNA changes. These results suggest that feedback control of ion channel expression may influence repolarization reserve.
Collapse
Affiliation(s)
- Ling Xiao
- From the Department of Medicine, Montreal Heart Institute and Université de Montréal (L.X., J.X., X.L., H.L., Z.W., S.N.), and Department of Pharmacology and Therapeutics, McGill University (L.X., S.N.), Montreal, Quebec, Canada
| | - Jiening Xiao
- From the Department of Medicine, Montreal Heart Institute and Université de Montréal (L.X., J.X., X.L., H.L., Z.W., S.N.), and Department of Pharmacology and Therapeutics, McGill University (L.X., S.N.), Montreal, Quebec, Canada
| | - Xiaobin Luo
- From the Department of Medicine, Montreal Heart Institute and Université de Montréal (L.X., J.X., X.L., H.L., Z.W., S.N.), and Department of Pharmacology and Therapeutics, McGill University (L.X., S.N.), Montreal, Quebec, Canada
| | - Huixian Lin
- From the Department of Medicine, Montreal Heart Institute and Université de Montréal (L.X., J.X., X.L., H.L., Z.W., S.N.), and Department of Pharmacology and Therapeutics, McGill University (L.X., S.N.), Montreal, Quebec, Canada
| | - Zhiguo Wang
- From the Department of Medicine, Montreal Heart Institute and Université de Montréal (L.X., J.X., X.L., H.L., Z.W., S.N.), and Department of Pharmacology and Therapeutics, McGill University (L.X., S.N.), Montreal, Quebec, Canada
| | - Stanley Nattel
- From the Department of Medicine, Montreal Heart Institute and Université de Montréal (L.X., J.X., X.L., H.L., Z.W., S.N.), and Department of Pharmacology and Therapeutics, McGill University (L.X., S.N.), Montreal, Quebec, Canada
| |
Collapse
|
14
|
Mohler PJ, Wehrens XHT. Mechanisms of human arrhythmia syndromes: abnormal cardiac macromolecular interactions. Physiology (Bethesda) 2008; 22:342-50. [PMID: 17928548 DOI: 10.1152/physiol.00018.2007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Many cardiac ion channels exist within macromolecular signaling complexes, comprised of pore-forming subunits that associate with auxiliary subunits, regulatory enzymes, and targeting proteins. This complex protein assembly ensures proper modulation of channel activity and ion homeostasis. The association of genetic defects in regulatory and targeting proteins to inherited arrhythmia syndromes has led to a better understanding of the critical role these proteins play in ion channel modulation.
Collapse
Affiliation(s)
- Peter J Mohler
- Department of Internal Medicine, Division of Cardiology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | | |
Collapse
|
15
|
Andreeva AV, Kutuzov MA, Voyno-Yasenetskaya TA. Scaffolding proteins in G-protein signaling. J Mol Signal 2007; 2:13. [PMID: 17971232 PMCID: PMC2211295 DOI: 10.1186/1750-2187-2-13] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2007] [Accepted: 10/30/2007] [Indexed: 11/18/2022] Open
Abstract
Heterotrimeric G proteins are ubiquitous signaling partners of seven transmembrane-domain G-protein-coupled receptors (GPCRs), the largest (and most important pharmacologically) receptor family in mammals. A number of scaffolding proteins have been identified that regulate various facets of GPCR signaling. In this review, we summarize current knowledge concerning those scaffolding proteins that are known to directly bind heterotrimeric G proteins, and discuss the composition of the protein complexes they assemble and their effects on signal transduction. Emerging evidence about possible ways of regulation of activity of these scaffolding proteins is also discussed.
Collapse
Affiliation(s)
- Alexandra V Andreeva
- Department of Pharmacology, College of Medicine, University of Illinois at Chicago, 909 S, Wolcott Ave, Chicago, Illinois 60612, USA.
| | | | | |
Collapse
|
16
|
van Oort RJ, Wehrens XHT. Subcellular targeting of phosphatases: a novel function of ankyrins. Am J Physiol Heart Circ Physiol 2007; 293:H15-6. [PMID: 17449551 DOI: 10.1152/ajpheart.00467.2007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
17
|
Richter C, West M, Odorizzi G. Dual mechanisms specify Doa4-mediated deubiquitination at multivesicular bodies. EMBO J 2007; 26:2454-64. [PMID: 17446860 PMCID: PMC1868904 DOI: 10.1038/sj.emboj.7601692] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2006] [Accepted: 03/29/2007] [Indexed: 12/23/2022] Open
Abstract
Doa4 is a ubiquitin-specific protease in Saccharomyces cerevisiae that deubiquitinates integral membrane proteins sorted into the lumenal vesicles of late-endosomal multivesicular bodies (MVBs). We show that the non-catalytic N terminus of Doa4 mediates its recruitment to endosomes through its association with Bro1, which is one of several highly conserved class E Vps proteins that comprise the core MVB sorting machinery. In turn, Bro1 directly stimulates deubiquitination by interacting with a YPxL motif in the catalytic domain of Doa4. Mutations in either Doa4 or Bro1 that disrupt catalytic activation of Doa4 impair deubiquitination and sorting of MVB cargo proteins and lead to the formation of lumenal MVB vesicles that are predominantly small compared with the vesicles seen in wild-type cells. Thus, by recruiting Doa4 to late endosomes and stimulating its catalytic activity, Bro1 fulfills a novel dual role in coordinating deubiquitination in the MVB pathway.
Collapse
Affiliation(s)
- Caleb Richter
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Matthew West
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Greg Odorizzi
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, USA
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, 347 UCB, Colorado Avenue, Boulder, CO 80309, USA. Tel.: +1 303 735 0179; Fax: +1 303 492 7744; E-mail:
| |
Collapse
|
18
|
Proceedings of the first International Meeting on Anchored cAMP Signaling Pathways, Biomedical Campus, Berlin-Buch, Germany, 15-16 October 2005. Eur J Cell Biol 2006; 85:581-697. [PMID: 16647785 DOI: 10.1016/j.ejcb.2006.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
|